A melt-blown polylactic acid liquid filter cloth, a preparation method and application thereof

Abstract

The application discloses a melt-blown polylactic acid liquid filter cloth and a preparation method and application thereof, and belongs to the technical field of polymer cloth. The melt-blown polylactic acid liquid filter cloth comprises the following components in weight fractions: 77-89 parts of polylactic acid resin; 10-20 parts of chitosan; 1-3 parts of graphene oxide; and 0.2-0.4 parts of an antioxidant. 2 The gram weight of the melt-blown polylactic acid liquid filter cloth is 10-100 g / m 2 ; and the average pore size of the melt-blown polylactic acid liquid filter cloth is 15-50 mu m. The melt-blown polylactic acid liquid filter cloth of the application effectively improves the dispersibility of graphene oxide by connecting chitosan with polylactic acid and graphene oxide respectively, thereby greatly improving the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth under the premise of ensuring the cloth breaking strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of non-woven filter cloth, more particularly to a melt-blown polylactic acid liquid filter cloth and a preparation method and application thereof. BACKGROUND

[0002] With the development of the national economy, liquid filtration has penetrated into various aspects of industry, agriculture, national defense, scientific research, etc. from the filtration of hydraulic systems in the aviation industry, aviation kerosene filtration to the filtration of mineral water, wine, fruit juice in the food and beverage industry; from the filtration of medicinal liquid, blood in the pharmaceutical and health industry to the filtration of oilfield water injection in the petroleum industry; from the filtration of organic solvents in the chemical industry to the pre-filtration of high-purity water in the electronic industry, etc. Its important role is obvious, and the development of liquid filter cloth has always been a problem that people strive to solve.

[0003] At present, the commonly used liquid filter cloth mainly includes metal mesh, textile cloth, glass fiber, inorganic non-metallic porous cloth and non-woven cloth. Among them, the non-woven cloth liquid filter cloth is a new type of fiber filter cloth, which has the advantages of easy compounding with other filter cloths, folding and molding in production, high filtration efficiency, low resistance and large dust capacity, etc. and gradually develops in the field of liquid filtration. Melt-blown non-woven cloth is widely used in the process of primary filtration and fine filtration in the field of liquid filtration due to its characteristics of fine fibers, high porosity and high production efficiency, but more than 90% of the melt-blown non-woven cloth currently uses polypropylene resin as the original cloth. The polypropylene melt-blown cloth is difficult to degrade naturally and is easy to cause white pollution after being discarded, while the emergence of polylactic acid can solve the above problems. Polylactic acid is widely available and biodegradable, so the preparation of polylactic acid melt-blown non-woven filter cloth has high social and economic value.

[0004] The polylactic acid melt-blown non-woven filter cloth applied in the field of liquid filtration not only can increase the liquid filtration flux, but also can reduce the generation of liquid filter waste, which meets the "double carbon" strategic development and needs to invest in basic research and industrialization application research.

[0005] The prior art discloses a biodegradable antibacterial polylactic acid anti-sticking non-woven cloth slice, which comprises polylactic acid, modified chitosan and a compatibilizer. The antibacterial performance and elongation at break are improved. However, it does not aim to improve the adsorption effect of melt-blown polylactic acid liquid filter cloth on heavy metal ions. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the defects and deficiencies of the existing melt-blown polylactic acid liquid filter cloth in poor adsorption effect on heavy metal ions, and to provide a melt-blown polylactic acid liquid filter cloth which can improve the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth under the premise of ensuring the cloth breaking strength.

[0007] The application further aims to provide a preparation method of the melt-blown polylactic acid liquid filter cloth.

[0008] The application further aims to provide an application of the melt-blown polylactic acid liquid filter cloth in the field of degradable filtration.

[0009] The above-mentioned purposes of the application are achieved by the following technical solutions.

[0010] The melt-blown polylactic acid liquid filter cloth comprises the following components in parts by weight:

[0011]

[0012] The melt-blown polylactic acid liquid filter cloth has a grammage of 10-100 g / m 2 ;

[0013] The melt-blown polylactic acid liquid filter cloth has an average pore size of 15-50 μm.

[0014] The application effectively improves the dispersibility of the graphene oxide under the premise of ensuring the breaking strength of the melt-blown polylactic acid liquid filter cloth, thereby greatly improving the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth.

[0015] The action mechanism of each component of the melt-blown polylactic acid liquid filter cloth of the application is as follows:

[0016] The esterification reaction of the carboxyl and the hydroxyl enables the chitosan to serve as a compatibility agent between the polylactic acid and the graphene oxide, which not only improves the dispersibility of the graphene oxide in the polylactic acid filter cloth, but also enables the polylactic acid filter cloth to permanently have the heavy metal adsorption capacity.

[0017] Preferably, the average flake size of the graphene oxide is 0.5-7 μm.

[0018] The flake size of the graphene oxide is detected by a transmission electron microscope, and the sample preparation method is as follows: ethanol is used as a dispersant, the graphene oxide is first prepared into a dispersion liquid by an ultrasonic method, is diluted to a light yellow color close to colorless, is ultrasonically dispersed for 10 min, is dropped on a copper mesh, and is naturally air-dried for 2 min for testing.

[0019] The calculation method of the average flake size is as follows: the flake sizes of 100 graphene oxide flakes are tested, and an average value is taken.

[0020] More preferably, the average flake size of the graphene oxide is 2-4 μm.

[0021] Optionally, the degree of deacetylation of the chitosan is 75%-95%.

[0022] The test method for deacetylation degree is: accurately weigh a quantitative chitosan sample, place it in a 250 mL triangular flask, add 0.1 mol / L hydrochloric acid standard solution, completely dissolve at 20-25°C, add 2-3 drops of methyl orange indicator, and titrate the free hydrochloric acid with 0.1 mol / L sodium hydroxide standard solution. Take another sample and place it in a 105°C oven to dry to the same weight, and measure the moisture content. Each sample is tested 3 times, and the deacetylation degree is calculated according to the following formula:

[0023] Theoretical amino content = 16 / 161 x 100% = 9.94%, wherein 16 is the molar mass of amino (g / mol), and 161 is the molar mass of chitosan unit (g / mol);

[0024] Amino content = (C1V1-C2V2) x 0.016 / G(100-W)

[0025] C1 is the concentration of hydrochloric acid standard solution (mol / L); C2 is the concentration of sodium hydroxide standard solution (mol / L);

[0026] V1 is the volume of hydrochloric acid standard solution (mL); V2 is the volume of sodium hydroxide standard solution (mL);

[0027] G is the sample weight; W is the moisture content of the sample (%); 0.016 is the amount of amino corresponding to the amount of substance of 1 mL of 1 mol / L hydrochloric acid (g);

[0028] Deacetylation degree = (amino content / theoretical amino content) x 100%.

[0029] Preferably, the deacetylation degree of the chitosan is 85%-90%.

[0030] Alternatively, the polylactic acid resin has a melt flow rate of 10-200 g / 10 min under the test conditions of 190°C and 2.16 kg, and the test standard is GB / T 3682.1-2018.

[0031] Preferably, the polylactic acid resin has a melt flow rate of 30-100 g / 10 min under the test conditions of 190°C and 2.16 kg, and the test standard is GB / T 3682.1-2018.

[0032] Preferably, the weight ratio of the chitosan to the graphene oxide is (5-10):1.

[0033] More preferably, the weight ratio of the chitosan to the graphene oxide is (7-9):1.

[0034] Preferably, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

[0035] The hindered phenol antioxidant can be antioxidant 1010.

[0036] The phosphite antioxidant can be antioxidant 168.

[0037] The weight ratio of the hindered phenol antioxidant and the phosphite antioxidant can be 1:1.

[0038] The antioxidant can improve the antioxidant effect of the melt-blown polylactic acid liquid filter cloth.

[0039] The application also protects a preparation method of the melt-blown polylactic acid liquid filter cloth, comprising the following steps: mixing components, melt-extruding through an extruder, granulating, and drying to obtain a polylactic acid composite material; and melt-blowing the polylactic acid composite material to obtain the melt-blown polylactic acid liquid filter cloth.

[0040] Preferably, the preparation method of the melt-blown polylactic acid liquid filter cloth comprises the following steps: mixing polylactic acid resin and chitosan, mixing the mixture with graphene oxide and an antioxidant, melt-extruding the mixture through an extruder, granulating, and drying to obtain a polylactic acid composite material; and melt-blowing the polylactic acid composite material to obtain the melt-blown polylactic acid liquid filter cloth.

[0041] The extruder can be a double-screw extruder.

[0042] The polylactic acid resin and the chitosan are mixed first, and the hydroxyl groups of the chitosan and the carboxyl groups on the polylactic acid molecular chain are subjected to esterification reaction, so that the chitosan is grafted to the polylactic acid molecular chain in situ. Then the mixture is mixed with graphene oxide, and the remaining hydroxyl groups of the chitosan and the carboxyl groups on the surface of the graphene oxide are subjected to reaction grafting, so that the dispersibility of the graphene oxide is improved. The melt-blown polylactic acid liquid filter cloth can greatly improve the heavy metal adsorption capacity.

[0043] The melt-blown polylactic acid liquid filter cloth prepared by the application has high heavy metal adsorption capacity and good mechanical strength, and can be widely applied to the preparation of liquid filter cloth. The application protects the application of the melt-blown polylactic acid liquid filter cloth in the liquid field.

[0044] The application especially protects the application of the melt-blown polylactic acid liquid filter cloth in the preparation of industrial wastewater purification cloth.

[0045] The melt-blown polylactic acid liquid filter cloth of the application is a degradable liquid filter cloth, which is endowed with heavy metal adsorption capacity, greatly expands the application field of the degradable liquid filter cloth, and has important economic value and strategic value.

[0046] Compared with the prior art, the application has the following beneficial effects:

[0047] The melt-blown polylactic acid liquid filter cloth of the present application comprises polylactic acid resin, chitosan, graphene oxide and antioxidant. The present application effectively improves the dispersibility of graphene oxide by connecting chitosan with polylactic acid and graphene oxide respectively, thereby greatly improving the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth under the premise of ensuring the breaking strength of the cloth. DETAILED DESCRIPTION

[0048] The present application will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present application in any form. Unless otherwise specified, the raw materials used in the embodiments of the present application are commercially available raw materials.

[0049] Polylactic acid resin A: PLA L130, Total Corbion PLA, melt mass flow rate of 10 g / 10 min at 190℃, 2.16 kg;

[0050] Polylactic acid resin B: PLA 6252D, Natureworks, USA, melt mass flow rate of 30 g / 10 min at 190℃, 2.16 kg;

[0051] Polylactic acid resin C: PLA-40, Anhui Fengyuan New Material Technology Co., Ltd., melt mass flow rate of 40 g / 10 min at 190℃, 2.16 kg;

[0052] Polylactic acid resin D: PLA-100, Anhui Fengyuan New Material Technology Co., Ltd., melt mass flow rate of 100 g / 10 min at 190℃, 2.16 kg;

[0053] Polylactic acid resin E: PLA-200, Anhui Fengyuan New Material Technology Co., Ltd., melt mass flow rate of 200 g / 10 min at 190℃, 2.16 kg;

[0054] Chitosan 1: degree of deacetylation 75%, model HY75, Sichuan Huayuan Shengtai Biological Technology Co., Ltd.;

[0055] Chitosan 2: degree of deacetylation 85%, model HY85, Sichuan Huayuan Shengtai Biological Technology Co., Ltd.;

[0056] Chitosan 3: degree of deacetylation 90%, model HY90, Sichuan Huayuan Shengtai Biological Technology Co., Ltd.;

[0057] Chitosan 4: degree of deacetylation 95%, model HY95, Sichuan Huayuan Shengtai Biological Technology Co., Ltd.;

[0058] Graphene oxide 1: average flake size 0.5um, XF002-1 brand, Jiangsu Xianfeng Nanometer Material Science and Technology Co., Ltd.

[0059] Graphene oxide 2: average flake size 2um, XF182-1 brand, Jiangsu Xianfeng Nanometer Material Science and Technology Co., Ltd.

[0060] Graphene oxide 3: average flake size 4um, XF002-2 brand, Jiangsu Xianfeng Nanometer Material Science and Technology Co., Ltd.

[0061] Graphene oxide 4: average flake size 7um, XF002-3 brand, Jiangsu Xianfeng Nanometer Material Science and Technology Co., Ltd.

[0062] Antioxidant, hindered phenolic antioxidant and phosphite antioxidant, the weight ratio of hindered phenolic antioxidant to phosphite antioxidant is 1:1, commercially available and the same kind is used in parallel examples and comparative examples.

[0063] Examples 1-15

[0064] A melt-blown polylactic acid liquid filter cloth, comprising the following components in parts by weight: polylactic acid resin; chitosan; graphene oxide; antioxidant.

[0065] The specific content of each component is shown in Table 1 below.

[0066] Table 1 Composition of melt-blown polylactic acid liquid filter cloth of each example (in parts by weight)

[0067] Components 1 2 3 4 5 Polylactic acid resin C 83 77 89 83 83 Chitosan 3 15 20 10 15.3 14.9 Graphene oxide 2 2 3 1 1.7 2.1 Antioxidant 0.3 0.2 0.4 0.3 0.3

[0068] Table 1 (continued)

[0069]

[0070]

[0071] The preparation method of the above-mentioned melt-blown polylactic acid liquid filter cloth comprises the following steps:

[0072] The polylactic acid resin and chitosan are first mixed with a low-speed mixer for 1 min; then the graphene oxide and antioxidant are added respectively and continue to mix for 1-2 min, with the rotation speed controlled at 30-50 r / min; the mixed material is added to a double-screw extruder for extrusion granulation to prepare a polylactic acid composite material, with the temperature of the extruder set at 140-180℃ and double-vacuum exhaust used.

[0073] The polylactic acid composite material is put into a single screw extruder of a melt blowing equipment system for melt extrusion, and then is metered by a metering pump and enters a melt blowing die system through a pipeline for melt distribution, is extruded from a spinneret hole, is drawn into superfine fibers by high temperature and high speed hot air, and is formed into a melt blown polylactic acid liquid filter cloth on a drum metal screen curtain by negative pressure suction and self thermal bonding.

[0074] The extrusion temperature of the melt blowing system is set to 220℃, the die temperature is set to 230℃, the hot air temperature is set to 240℃, the hot air frequency is set to 30Hz, the screen curtain receiving distance is set to 10cm, the metering pump frequency is 5Hz, and the linear speed is 6m / min.

[0075] The melt blown polylactic acid liquid filter cloth prepared in Examples 1-15 has a grammage of 35g / m 2 .

[0076] Example 16

[0077] A melt blown polylactic acid liquid filter cloth, which has the same material formula and grammage as Example 1. The difference from Example 1 is the preparation method of the melt blown polylactic acid liquid filter cloth, which comprises the following steps: mixing polylactic acid resin, chitosan, graphene oxide and antioxidant, melt extruding and granulating the mixture by a double screw extruder to obtain a polylactic acid composite material, and finally preparing a melt blown polylactic acid liquid filter cloth by melt blowing.

[0078] Mix polylactic acid resin, chitosan, graphene oxide and antioxidant for 3min, and control the rotation speed at 30-50r / min; extrude and granulate the mixed material by a double screw extruder to prepare a polylactic acid composite material, and set the temperature of the extruder to 140-180℃ and adopt double vacuum exhaust.

[0079] The polylactic acid composite material is put into a single screw extruder of a melt blowing equipment system for melt extrusion, and then is metered by a metering pump and enters a melt blowing die system through a pipeline for melt distribution, is extruded from a spinneret hole, is drawn into superfine fibers by high temperature and high speed hot air, and is formed into a melt blown polylactic acid liquid filter cloth on a drum metal screen curtain by negative pressure suction and self thermal bonding.

[0080] The extrusion temperature of the melt blowing system is set to 220℃, the die temperature is set to 230℃, the hot air temperature is set to 240℃, the hot air frequency is set to 30Hz, the screen curtain receiving distance is set to 10cm, the metering pump frequency is 5Hz, and the linear speed is 6m / min.

[0081] Example 17

[0082] A melt blown polylactic acid liquid filter cloth, which has the same material formula as Example 1. The difference from Example 1 is that:

[0083] The extrusion temperature of the melt-blowing system was set to 220°C, the die temperature was set to 230°C, the hot air temperature was set to 240°C, the hot air frequency was set to 30Hz, and the screen curtain receiving distance was set to 10cm; the metering pump frequency was 2Hz, and the linear speed was 6m / min.

[0084] The melt-blown polylactic acid liquid filter cloth prepared in Example 17 had a grammage of 10g / m 2 .

[0085] Example 18

[0086] A melt-blown polylactic acid liquid filter cloth, which had the same material formula and grammage as Example 1. The difference from Example 1 was that:

[0087] The extrusion temperature of the melt-blowing system was set to 220°C, the die temperature was set to 230°C, the hot air temperature was set to 240°C, the hot air frequency was set to 30Hz, and the screen curtain receiving distance was set to 10cm; the metering pump frequency was 20Hz, and the linear speed was 6m / min.

[0088] The melt-blown polylactic acid liquid filter cloth prepared in Example 18 had an average pore size of 100μm. 2 .

[0089] Example 19

[0090] A melt-blown polylactic acid liquid filter cloth, which had the same material formula and grammage as Example 1. The difference from Example 1 was that:

[0091] The extrusion temperature of the melt-blowing system was set to 220°C, the die temperature was set to 230°C, the hot air temperature was set to 220°C, the hot air frequency was set to 20Hz, and the screen curtain receiving distance was set to 10cm; the metering pump frequency was 5Hz, and the linear speed was 6m / min.

[0092] The melt-blown polylactic acid liquid filter cloth prepared in Example 19 had an average pore size of 50μm.

[0093] Comparative Examples 1-4

[0094] A melt-blown polylactic acid liquid filter cloth, which included the following components in parts by weight: polylactic acid resin; chitosan; graphene oxide; and antioxidant.

[0095] The specific content of each component is shown in Table 2 below.

[0096] Table 2 Composition of the melt-blown polylactic acid liquid filter cloth of each comparative example (in parts by weight)

[0097] Components Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Polylactic acid resin C 83 68 83 81 Chitosan 3 0 30 15 15 Graphene oxide 2 2 2 0 4 Antioxidant 0.3 0.3 0.3 0.3

[0098] The preparation method of the melt-blown polylactic acid liquid filter cloth and the melt-blown process of Example 1 are the same, and details are not repeated here.

[0099] Comparative Example 5

[0100] A melt-blown polylactic acid liquid filter cloth was prepared with the same material formula as Example 1. The difference from Example 1 is that:

[0101] The extrusion temperature of the melt-blown system was set to 220℃, the die temperature was set to 230℃, the hot air temperature was set to 240℃, the hot air frequency was set to 30Hz, and the screen curtain receiving distance was set to 10cm; the metering pump frequency was 22Hz, and the linear speed was 6m / min.

[0102] The melt-blown polylactic acid liquid filter cloth prepared in Comparative Example 5 had a grammage of 110g / m 2 .

[0103] Results detection

[0104] The melt-blown polylactic acid liquid filter cloth prepared in each example and comparative example was tested according to the following method:

[0105] (1) Heavy metal adsorption capacity: 200mL of aqueous solution containing Hg 2+ (10.0ppm), Pb 2+ (30.0ppm) respectively was prepared, melt-blown polylactic acid liquid filter cloth (500mg) prepared in each example and comparative example was added and uniformly dispersed, and shaken for 20min for adsorption. The content of Hg 2+ , Pb 2+ in the extract before and after adsorption was determined, and the removal performance of the heavy metal adsorbent was evaluated by the change in ion concentration before and after adsorption.

[0106] (2) Breaking strength: tested according to GB / T 24218.3-2010 standard, sample size: 50mm*300mm, tensile rate: 300mm / min.

[0107] (3) Average pore size: tested according to GB / T 32361-2015 standard, using ethanol immersion and N2 displacement.

[0108] The specific test results of the melt-blown polylactic acid liquid filter cloth of each example and comparative example are shown in Table 3 below:

[0109] Table 3

[0110]

[0111] From the above data, it can be seen that the melt-blown polylactic acid liquid filter cloth of the present application can not only have high breaking strength, but also can adsorb heavy metal ions.

[0112] When the grammage of the melt-blown polylactic acid liquid filter cloth is 10-100 g / m 2 , the breaking strength of the melt-blown polylactic acid liquid filter cloth of the present application can reach 15.2 N or more, 15.2-25.6 N, Hg 2+ , the adsorption rate can reach 95.2% or more, 95.2-99.7%, Pb 2+ , the adsorption rate can reach 94.6% or more, 94.6-99.4%, and the average pore size is 19.9-50 μm.

[0113] When the grammage of the melt-blown polylactic acid liquid filter cloth is 35 g / m 2 , the breaking strength of the melt-blown polylactic acid liquid filter cloth of the present application can reach 22.0-25.6 N, Hg 2+ , the adsorption rate can reach 97.5-99.7%, Pb 2+ , the adsorption rate can reach 97.0-99.4%, and the average pore size is 19.9-24.5 μm.

[0114] As can be seen from Comparative Example 1, the breaking strength and heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth are too low, because the chitosan is too little, the dispersibility of graphene oxide is reduced, thereby causing the breaking strength and heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth to decrease more obviously.

[0115] As can be seen from Comparative Example 2, the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth is too poor, because the chitosan is too much, on the one hand, the flowability of the melt-blown polylactic acid liquid filter cloth is reduced, and on the other hand, the proportion of graphene oxide is diluted, thereby reducing the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth.

[0116] As can be seen from Comparative Example 3, the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth is greatly reduced because the graphene oxide is too little.

[0117] As can be seen from Comparative Example 4, the breaking strength of the melt-blown polylactic acid liquid filter cloth is too low, because the graphene oxide is too much, the excess graphene oxide cannot be grafted onto the chitosan, the compatibility between the graphene oxide and the polylactic acid resin is reduced, thereby reducing the breaking strength of the melt-blown polylactic acid liquid filter cloth.

[0118] As can be seen from Examples 1-5, when the weight ratio of chitosan to graphene oxide is (7-9):1, the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth is more excellent, because the weight ratio of chitosan to graphene oxide in this range is more conducive to improving the grafting of graphene oxide on chitosan, thereby further improving the dispersibility of graphene oxide and increasing the heavy metal adsorption capacity of the melt-blown polylactic acid liquid filter cloth.

[0119] As can be seen from Example 1, Example 6 to Example 9, the melt flow rate of the polylactic acid resin is 30 to 100 g / 10 min, and the melt-blown polylactic acid liquid filter cloth has better heavy metal adsorption capacity, because the polylactic acid resin with the melt flow rate in this range is more conducive to the dispersibility of graphene oxide and the reduction of the average pore size, and therefore the prepared melt-blown polylactic acid liquid filter cloth has excellent heavy metal adsorption performance. When the melt flow rate is low, the molecular weight is large, and it is not easy to stretch into ultra-fine fibers during the melt-blown process, the fiber diameter is large, the average pore size is large, and the heavy metal adsorption performance of the prepared liquid filter cloth is reduced. When the melt flow rate is high, the dispersibility of chitosan in the polylactic acid melt is reduced, which is not conducive to the uniform grafting of chitosan, and thus is not conducive to the dispersibility of graphene oxide, reducing the adsorption performance of the liquid filter cloth.

[0120] As can be seen from Example 1, Example 10 to Example 12, when the average pore size is similar to the grammage, the deacetylation degree of chitosan is 85% to 90%, and the melt-blown polylactic acid liquid filter cloth has better heavy metal adsorption capacity and breaking strength, because the chitosan with the deacetylation degree in this range is more conducive to improving the dispersibility of graphene oxide, and therefore has better adsorption effect on heavy metal ions. Because when the deacetylation degree is low, the content of surface hydroxyl groups is low, which is not conducive to the grafting on the polylactic acid molecular chain, and thus reduces the dispersibility of graphene oxide in the polylactic acid resin, reducing the adsorption capacity of the melt-blown polylactic acid liquid filter cloth. When the deacetylation degree is too high, it will preferentially increase the grafting capacity with polylactic acid, thereby reducing the amount of graphene oxide grafted on chitosan, and also reducing the dispersibility of graphene oxide in the polylactic acid resin, thereby reducing the heavy metal adsorption capacity and breaking strength of the melt-blown polylactic acid liquid filter cloth.

[0121] As can be seen from Example 1, Example 13 to Example 15, the average flake diameter of graphene oxide is 2 to 4 μm, which is more conducive to improving the breaking strength and heavy metal adsorption capacity while preventing the occurrence of crystal points. Because when the average flake diameter of graphene oxide is low, it is easy to agglomerate during the melt-blown production process, block the spinneret, cause the spinning to be not smooth, and produce crystal points; when the average flake diameter is high, it is easy to form obvious defect points in the interior of the polylactic acid melt-blown fiber, reducing the breaking strength of the fiber, and at the same time, the high average flake diameter will reduce the specific surface area of graphene oxide, thereby reducing the adsorption capacity of the melt-blown polylactic acid liquid filter cloth.

[0122] As can be seen from Example 1, Example 16, mixing polylactic acid resin and chitosan, and then mixing with graphene oxide and antioxidant, is more conducive to the dispersibility of graphene oxide, and therefore is more conducive to improving the heavy metal adsorption capacity and breaking strength of the melt-blown polylactic acid liquid filter cloth.

[0123] As can be seen from Example 1, Example 17, Example 18 and Comparative Example 5, the grammage of the melt-blown polylactic acid liquid filter cloth also affects the heavy metal adsorption rate and the breaking strength, because when the fiber diameter is the same, the higher the grammage, the greater the number of fibers and porosity per unit area, thereby increasing the heavy metal adsorption capacity and breaking strength of the liquid filter cloth. However, as the grammage increases, it will cause the melt-blown polylactic acid fibers to be difficult to stretch into fine fibers, the fiber diameter becomes thicker, the average pore size becomes larger, and the breaking strength and heavy metal adsorption rate of the liquid filter cloth will decrease to some extent. When the grammage is increased to a high enough level, the fiber diameter and average pore size will increase too much, thereby causing the heavy metal adsorption capacity and breaking strength of the liquid filter cloth to decrease significantly.

[0124] As can be seen from Example 1 and Example 19, the average pore size of the melt-blown polylactic acid liquid filter cloth mainly affects the heavy metal adsorption rate of the liquid filter cloth, and the smaller the average pore size, the higher the heavy metal adsorption rate.

[0125] Obviously, the above embodiments of the present application are merely exemplary and are not intended to limit the embodiments of the present application. Based on the above description, those skilled in the art can make other different forms of changes or modifications. It is not necessary or possible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A melt-blown polylactic acid liquid filtration cloth, characterized by, The poly lactic acid resin is 77-89 parts by weight; The chitosan is 10-20 parts by weight; The graphene oxide is 1-3 parts by weight; The antioxidant is 0.2-0.4 parts by weight; The average pore size of the melt-blown poly lactic acid liquid filter cloth is 15-50 microns; The melt-blown polylactic acid liquid filter cloth has a grammage of 35 g / m2~100 g / m2 2 ; The weight ratio of the chitosan to the graphene oxide is (20:3)-(10:1). The average flake size of the graphene oxide is 0.5-7 microns.

2. The melt-blown polylactic acid liquid filtration fabric of claim 1, wherein, The average flake size of the graphene oxide is 2-4 microns.

3. The melt-blown polylactic acid liquid filtration fabric of claim 2, wherein, The degree of deacetylation of the chitosan is 75%-95%.

4. The melt-blown polylactic acid liquid filtration fabric of claim 1, wherein, The melt flow rate of the poly lactic acid resin is 10-200 g / 10 min at 190 DEG C under a test condition of 2.16 kg, and the test standard is GB / T 3682.1-2018.

5. The melt-blown polylactic acid liquid filtration fabric of claim 1, wherein, The weight ratio of the chitosan to the graphene oxide is (7-9):

1.

6. The melt-blown polylactic acid liquid filtration fabric of claim 1, wherein, The antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

7. The melt-blown polylactic acid liquid filtration fabric of claim 1, wherein, The poly lactic acid composite material is obtained by mixing the components, melt-extruding and granulating through an extruder, and drying.

8. The process for producing the melt-blown polylactic acid liquid filtration cloth according to any one of claims 1 to 7, characterized by, 9. The melt-blown poly lactic acid liquid filter cloth according to any one of claims 1-7 is applied in the field of liquid filtration. ​

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